The present disclosure relates generally to image forming optical systems, such as night vision devices, and, more particularly, to attachments for adjusting optical properties of image forming optical systems.
U.S. Pat. No. 5,760,953 discloses an adaptor for night vision goggles and U.S. Pat. No. 5,617,257 discloses a variable focus adaptor for night vision goggles, and both are incorporated by reference.